Solar Home FAQs

I've seen some people who use solar and other renewable energies, and their houses seem thrown-together and weird. Can I have an energy-efficient home that looks like other homes in the neighborhood? Can it look "normal"?

Our goal in developing our Sun-Inspired Home Plans was to create passive solar homes for the twenty-first century that incorporate inviting exteriors and functional floor plans. The exterior styles incorporate the design elements found in a variety of housing throughout the country. The floor plans allow for the changing needs of individuals. The energy-efficient aspect of the designs has no effect on the design. The passive solar design requires more windows on the south, and the primary negative aspect of this is that the south side of the house cannot have a covered porch, as this would block the sun.

How important is the home's design in maximizing energy efficiency? Can't I just weather-strip the doors and throw some solar panels on the south side?

There are three aspects that go into making a good passive solar home:

1. The design and orientation of the home
2. An energy-efficient envelope (the parts of the building structure that interface with the outdoors)
3. A well designed and installed heating and/or cooling system

Each of the above affects the energy savings by about a third. So even if you cannot have south windows for solar gain (item 1), you can still incorporate items 2 (which would include weather-stripping) and 3.

The above items refer to passive solar gain, which is taking advantage of the sun's free heat as it enters windows. Good passive solar design also keeps out the sun in the hot months with properly placed windows and porches, and properly designed window overhangs.

Active solar involves additional systems to take advantage of the sun's heat. The most commonly seen components are the panels on the roof. These panels are most commonly used to heat water, and are tied into the conventional hot water systems of the house. The other type of panels are PV (photovoltaic) panels that turn the sun's energy into electricity. These electricity from these panels is most commonly stored in batteries and can then be used by the electrical items in the house such as lights or any items that plug into outlets.

A home can incorporate active solar or passive solar or both. Our Sun-Inspired Home Plans incorporate passive solar design, and are compatible with active solar systems.

In what ways does the home design contribute to better use of solar energy?

Good passive solar home design maximizes the amount of windows on the south, but balances the amount of south glass with thermal mass inside. Houses in hot climates can get by with less glass on the south, and therefore require no additional thermal mass for comfort. Good passive solar design also incorporates the strategies mentioned above to prevent overheating. It also takes into account the lifestyle of the occupants and the lot or land orientation, slope, and views. All of these affect which rooms will be placed on the south side of the house. A well-designed home should fit the occupants like a glove, and balance passive solar design, floor plans desires, and exterior style as well as the lay of the land and climate.

What's passive solar, and does it offer enough warmth to heat my home? Can I "turn it off" in the summer?

Passive solar is defined in the second question above. The amount of heat that is supplied depends upon factors such as the location in the country, the house design, and the amount of insulation. Warmer climates reach higher heating levels with fewer solar features. More south windows can usually be incorporated into two-story houses, and those with long south walls. Homes with more insulation lose less heat, so the sun supplies a greater fraction of the overall heat needed.

It is possible for the sun to supply close to 100% of your homes heating needs, but to achieve such high percentages is not usually cost effective. We strive for 25% to 40% of a home's heating needs, which keeps the upgrades very cost effective—usually no more than a 10% increase in costs, and often less. This 10% cost increase typically includes the passive solar items, the energy-efficient envelope, and the heating and/or cooling systems.

It is not possible (or necesary) to "turn off" passive solar heat with a switch, but there are ways to reduce the heat in the summer. The most effective way is with window overhangs properly designed for your climate and latitude. The overhang should let in the low winter sun, but keep out the high summer sun and hot afternoon sun. It is also possible to use adjustable and movable insulation and awnings for even further control.

My main question has to do with which plans might be appropriate for our climate .....The weather here in summer is hot and humid (95 – 100 degrees and 95 – 100% humidity). I would never consider opening the windows (high or low) to let the cooled air inside the house escape. It remains hot at night. In winter, it’s cold.... maybe snow once a year, melting within a week).

The goal with most of our plans it to maximize passive solar heating and cooling. For instance, in my own house we have still not turned on the ac this year (it's mid May) and at night time ventilation continues to cool the house when we close it up in the morning before we leave for the day. The temperature has yet to get above 76 inside even though daytime temperatures reach into the 80's. As a rule, we turn on our ac a month later than everyone else and the heat goes on a month later too and goes off one month sooner. Of course even so, our energy bills are about 1/3 of the neighbors when the auxillary heating and cooling is running.

You can apply passive cooling with any of our house plans if you are willing to be somewhat active, but the ones with greater distance between high and low windows (even basement to first floor) would work better. With a one story home, the "stack effect is less", but the ones with concrete slabs have more mass which also helps with cooling. So instead of recommending a plan, I might just say to stay away from one story plans with crawlspaces as they have the least amount of "stack effect." Also, please stay away from the ones designed to sit at a 45 degree angle such as most of the atrium plans - they are too difficult to control heat gain in late summer sun. (Many people still like those plan for design reasons and then we specify a glass with a low SHGC on the SW windows.)

Of course our custom energy recommendations that come with blueprints, erasable vellums, and CAD files tweak the home to your area. When you place the order, feel free to send us a list of your concerns and I'll address them simultaneously. If you want help prior to placing an order, we do have consulting on our pre-designed plans that starts out similar to the custom changes that we used to offer and may still again if our work load gets more under control. Please review our custom services and remember that with a custom designed home, we start with YOUR priorities unlike purchasing a pre-designed plan where we adapt someone else's priorities to best fit yours.

Is it possible to design and build an energy-efficient home that fits my family's needs without having to get three jobs to pay for it?

A sun-tempered home has less south glass than a full passive solar version. It has no more windows than a conventional home, but most of them are located on the south. It requires no additional thermal mass for comfort. A sun-tempered home therefore costs no more than any other well-insulated home with a tight envelope and a high quality, well-installed heating and/or cooling system.

The energy-efficient envelope and mechanical system will typically cost 2-4% more in construction costs, but the amount they add to your mortgage payment will be much less than the energy savings they result in. (For example, the mortgage payment may increase by $30 per month, but your energy savings may be $75 per month less than your neighbor's home built by the popular builder in the new subdivision.)

A well-insulated home can be achieved with conventional stud walls and cellulose insulation, and the extra cost are typically a part of the 2-4% increase. Sun-tempering is appropriate for the lower and middle latitudes of the country. Our blueprint orders come with custom energy recommendations for the homeowner's climate.

As previously mentioned, the full passive solar version in our Sun-Inspired Home Plans may add another 5% average to the construction costs. The savings will be at least 10% more than the sun-tempered version, and if costs are of little concern, much higher saving can be achieved. Many of our clients request that we adapt the home to be constructed with ICF's (insulated concrete forms) and SIP's (structurally insulated panels) that increase the costs and energy efficiency more than stud walls with fiberglass, which is seldom properly installed.

Does it matter what I build my house with—brick, logs, etc? What's your preference?

The exterior materials over a conventional stud wall have little effect on the energy performance of the home. Because it the most common type of construction—and therefore the method most familiar to builders—our homes are mostly designed around the stud walls system for cost effectiveness.

However, we realize that many people prefer log construction, ICF, SIP, or other materials for the walls. The inherent mass in the walls of many of these alternative materials works well in homes that cannot have the necessary thermal mass in the floors, but their construction cost is often higher. Slab-on-grade construction is the most economical way to get thermal mass in a home. With conventional construction, we also often install brick veneer on the outside of the stud walls.

What special adjustments do you make to your house designs to accommodate solar hot water panels?

Although our home designs do not include active solar systems, we design most of our roofs to include angles and orientations that allow for the easy installation of hot water and photovoltaic (PV) panels. This usually involves a large expanse of south-facing roof. For our custom designs, we can design the roof to optimize the orientation of the panels based on the recommendations of those designing your hot water or PV system.

What are a few, quick tips to choosing the perfect lot on which to build?

The so-called "perfect lot" for a solar home would have as few restrictions as possible. Of critical importance is a sunny south side or solar easement. Few trees would shade this area in the winter, and there would be no tall mountains or buildings on the south that would shade the south wall of the house in winter.

Privacy is usually wanted on this south side with many windows, so look for land where a neighbor cannot build to the south. With its many windows, the south side should also have great views. Although windows can be on the north, east, and west walls, they are usually an energy compromise.

Many people want a porch on the front of their house, and if this is the case, the front of the house cannot face south, as the porch would eliminate solar gain. Porches work well on the east and west as they can also shade the hot morning and afternoon sun in the summer, and of course the north side is also a good place for a front porch.

Our builder wants to use a window that meets the R-value that came with your custom energy recommendations, but not the SHGC (solar heat gain coefficient). The windows (actually the glass) SHGC of the manufacturer he wants to use range from 0.29 to 0.34. Your recommendations state 0.52 min. How much of a problem would this present?

You would receive approx. 40% less solar gain.

When I called the window manufacturer to ask about higher SHGC glass in my windows, they said clear glass was the only alternative they could offer.

Our custom energy recommendations state the SHGC that you should use for your south facing and other windows based on the climate that you live in. In some climates, clear glass is a good alternative for the south windows, especially if you will add interior insulated window shades on cold nights. We recommend specific glass types (rather than specific windows) for each of the major glass manufacturers such as AFG, PPG, Cardinal, and Pilkington LOF. They each make several with various SHGC values, and some of them cut out way too much of the sun that our passive solar homes are designed to let in. We recommend choosing a glass as close to what we have specified for your area as possible.

We are 11 degrees off from true south here in SE New York, I think. So if I stand at the NE corner of the house as currently staked out on the ground at the building site, and I point my compass at the SE corner of the house (along the exact line, therefore, of the E wall) should the SE corner be 11 degrees to the right of S (slightly SW) or to the left of the S (slightly SE) for the house to be facing true south?

That depends on whether your area's magnetic declination is east or west of true north. A surveyor will know specifics. A preliminary check shows that SE New York is about 13 degrees west of north (please see http://www.spacecom.com/customer_tools/images/us_mag_declination.gif for more info).

So based on that, true south would be 13 degrees to the west of the south arrow. The south arrow on the compass will actually point 13 degrees east of true south.

Can you help me find magnetic declination for my area? My surveyor is not sure.

This link will help you find magnetic declination for your area: www.geolab.nrcan.gc.ca/geomag/mirp_e.shtml.

Here is a graphic version, which may be a little outdated, but good for visualization: http://www.spacecom.com/customer_tools/images/us_mag_declination.gif

If the declination shows west, then rotate the house clockwise that many degrees from magnetic north as the compass shows. If the declination is east, then rotate the house counterclockwise that many degrees.

Since I can't visit the site when the summer sun is low (I live too far away and need to know now), can you help me determine whether or not the trees to the south will shade my house?

As noted on your drawings, the area to the south of your home should be left clear of shade-producing items. The most foolproof way to do this is to visit your site and do your clearing when the sun is the lowest on Dec. 21 and through the coldest winter months. Otherwise you can calculate it mathematically with a little trigonometry—specifically tangents if you know the height of the shade producing item (usually a tree, but can also be buildings or mountains) and your latitude.

Draw a triangle which represents a section through your site with the vertical side being the tree. The small angle at the bottom which starts at the south wall of your house would be the sun angle on December 21. On Dec. 21 at noon, the angle is 67° less your latitude, which is the small angle of the triangle. You can then solve for the unknown which is b or the horizontal distance the south side of your house needs to be from the trees at noon. Trees need to be further away from 9-3 p.m. so you may also want to look up your sun angle at the www.susdesign.com web site and calculate for those times and angles. Don't forget to send Christopher (the author of that web site) $25 for the use of his web tools.

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